An air conditioner is a device that is placed in a house, an office, a shop, a green house, or the like and maintains indoor environment to be comfortable for people to live or to be suitable for growing crops by adjusting temperature, humidity, cleanliness and airflow.
Particularly, an indoor temperature is a key factor of conditions for a comfortable sleep. Most sleep algorithms are configured to control an indoor temperature and maintain an adequate indoor temperature for user's comfortable sleep.
The sleep algorithm applied to the conventional air conditioner has a temperature control algorithm applicable to most people by static analysis. To be specific, the sleep algorithm has a sleep entrance mode to keep a temperature down for helping a user to get into sleep quickly at the early stage, a comfortable sleep temperature mode for helping the user to get into deep sleep and a wake-up mode for helping the user to wake up. According to the conventional technology, the sleep algorithm is implemented by controlling airflow for uniformly air conditioning an entire area using a conventional mixing system.
However, the electric charge for using an air conditioner is overwhelmingly expensive for those who use it in hot summer, especially when tropical nights last. The conventional technology has an energy reduction effect compared to a fixed temperature air conditioning operation in terms of temperature algorithm, but also consumes unnecessary energy for air conditioning even an area where a user does not stay (an area above 1 m height). To be specific, the conventional technology has the problem of consuming additional energy by uniformly air conditioning an area from 0 to 2 m height within a temperature variation of 3° C., particularly, air conditioning an area where a user does not stay for a sleep.